Image capturing apparatus, method thereof, and storage medium

Abstract

An image capturing apparatus comprises an image sensor that receives beams of reflected light from a subject incident via an imaging optical system whose wavelength that reaches a light-receiving surface is different in accordance with an angle of incidence of reflected light, and generates an image signal. The apparatus changes a state of the imaging optical system or the image sensor such that a second image signal is generated by beams for which the angle of incidence of the reflected light from the imaging optical system is different from the beams by which a first image signal is generated. The apparatus outputs a spectral image based on a plurality of the image signals generated by receiving the beams in different state of the imaging optical system or the image sensor.

What is claimed is: 
     
       1. An image capturing apparatus comprising:
 an image sensor configured to receive beams of reflected light from a subject incident via an imaging optical system whose wavelength that reaches a light-receiving surface is different in accordance with an angle of incidence of reflected light, and generate an image signal; 
 one or more processors; and 
 a memory configured to store instructions which, when the instructions are executed by the one or more processors, cause the image capturing apparatus to function as:
 a control unit that changes a state of the imaging optical system or the image sensor such that a second image signal is generated by beams for which the angle of incidence of the reflected light from the imaging optical system is different from the beams by which a first image signal is generated, wherein the control unit includes a driving unit that changes a relative position or direction between in optical system and the image sensor so as to change the angle of incidence of the reflected light from the imaging optical system; and 
 an output unit that outputs a spectral image based on a plurality of the image signals generated by receiving the beams in each state of the imaging optical system or the image sensor changed by the control unit, 
 
 wherein the driving unit changes the relative position between the imaging optical system and the image sensor by a shift amount by moving at least one of the imaging optical system and the image sensor on a plane that is parallel to the light-receiving surface, the shift amount being defined based on a subject distance of the subject. 
 
     
     
       2. The image capturing apparatus according to  claim 1 , wherein the shift amount is defined based on the subject distance of the subject, a pupil distance of the imaging optical system, and a movement amount from a predetermined position of the image capturing apparatus. 
     
     
       3. The image capturing apparatus according to  claim 1 , wherein the driving unit moves the imaging optical system or the image sensor to the relative position between the imaging optical system and the image sensor set in accordance with a desired range of wavelengths in the spectral image. 
     
     
       4. The image capturing apparatus according to  claim 3 , wherein resolution of the desired wavelengths in the spectral image is different in accordance with the number of image signals generated in a range in which the relative position is changed. 
     
     
       5. The image capturing apparatus according to  claim 1 , wherein the spectral image has a signal value for each unit specified by a spatial coordinate that corresponds to the light-receiving surface and a wavelength. 
     
     
       6. The image capturing apparatus according to  claim 1 , wherein the image sensor includes an optical element whose wavelength of a beam to be transmitted is different in accordance with the angle of incidence of the reflected light. 
     
     
       7. The image capturing apparatus according to  claim 6 , wherein the optical element is arranged on the image sensor that receives the beam. 
     
     
       8. The image capturing apparatus according to  claim 6 , wherein the optical element is configured by a dielectric multilayer film. 
     
     
       9. The image capturing apparatus according to  claim 6 , wherein the optical element is configured by a photonic crystal. 
     
     
       10. The image capturing apparatus according to  claim 6 , wherein the optical element is configured by a plasmonic crystal. 
     
     
       11. The image capturing apparatus according to  claim 1 , wherein a characteristic receiving the beam whose wavelength that reaches the light-receiving surface is different in accordance with the angle of incidence of the reflected light includes an angular dependency related to an angle of incidence in a two-dimensional direction with respect to a plane that is parallel to the light-receiving surface. 
     
     
       12. The image capturing apparatus according to  claim 1 , wherein the angle of incidence of the beam that reaches the light-receiving surface is configured to be approximately linear in relation to the shift amount. 
     
     
       13. The image capturing apparatus according to  claim 1 , wherein the angle of incidence of the beam that reaches the light-receiving surface is configured to be approximately linear in relation to a position of the light-receiving surface. 
     
     
       14. A method of controlling an image capturing apparatus that includes an image sensor operable to receive beams whose wavelength that reaches a light-receiving surface is different in accordance with an angle of incidence of reflected light among the reflected light from a subject incident via an imaging optical system, and generate an image signal, the method comprising:
 controlling to change a state of the imaging optical system or the image sensor such that a second image signal is generated by beams whose angle of incidence of the reflected light from the imaging optical system is different from beams by which a first image signal is generated, wherein the controlling to change the state of the imaging optical system or the image sensor includes changing a relative position or direction between the imaging optical system and the image sensor so as to change the angle of incidence of the reflected light from the imaging optical system; and 
 outputting a spectral image based on a plurality of the image signals generated by receiving the beams in each state of the imaging optical system or the image sensor changed by the control unit, 
 wherein the relative position between the imaging optical system and the image sensor is changed by a shift amount by moving at least one of the imaging optical system and the image sensor on a plane that is parallel to the light-receiving surface, the shift amount being defined based on a subject distance of the subject. 
 
     
     
       15. A non-transitory computer-readable storage medium comprising instructions for performing a method of controlling an image capturing apparatus that includes an image sensor operable to receive beams whose wavelength that reaches a light-receiving surface is different in accordance with an angle of incidence of reflected light among the reflected light from a subject incident via an imaging optical system, and generate an image signal, the method comprising:
 controlling to change a state of the imaging optical system or the image sensor such that a second image signal is generated by beams whose angle of incidence of the reflected light from the imaging optical system is different from beams by which a first image signal is generated, wherein the controlling to change the state of the imaging optical system or the image sensor includes changing a relative position or direction between the imaging optical system and the image sensor so as to change the angle of incidence of the reflected light from the imaging optical system; and 
 outputting a spectral image based on a plurality of the image signals generated by receiving the beams in each state of the imaging optical system or the image sensor changed by the control unit, 
 wherein the relative position between the imaging optical system and the image sensor is changed by a shift amount by moving at least one of the imaging optical system and the image sensor on a plane that is parallel to the light-receiving surface, the shift amount being defined based on a subject distance of the subject.